Apparatus for making contact discs



' nu- J'une 1, 190:; w. M. MAKI APPARATUS FOR MAKING CONTACT DISCS 4 Sheets-Sheet 1 Filed May 8, 1961 5 R v mm w MA @R W m M MWA M J] Hum 0 w 5 m u M M w June 1, 1965 w. M. MAKI 3,186,133

APPARATUS FOR MAKING CONTACT DISCS Filed May 8, 1961 4 Sheets-Sheet 2 I INVENTOR m r; WILL/AM M. MAK/ TORNE YS June 1, 1965 w. M. MAKl APPARATUS FOR MAKING- CONTACT DISCS 4 Sheets-Sheet 5 Filed May 8, 1961 ADVANC E RETURN ADVANCE RE TU RN INVENTOR. gg/LL/AM MMAK/ xizfiza'clz rprms 55% ffamf/ffimmf ATTORNEYS June 1, 1965 w. M. MAKI 3,186,133

APPARATUS FOR MAKING CONTACT DISCS Filed May 8, 1961 4 sheets-sneetu 32\ 93LADVANCE i RE TURN 9 39 3 4 9a ADVANCE x. 89 WWETURN I5 Fiq. 8

INVENTOR. F7 5 ILLIAM MMAK/ ATTORNE Y5 United States Patent 3,186,133 APPARATUS FOR MAKING CONTACT DISCS Wiiliam M. Maid, Libertyville, 151., assignor to Fansteel Metallurgical Corporation, a corporation of New York Filed May 8, 1961, Ser. No. 108,447 8 Claims. (Cl. 51-105) This invention relates to electrical contacts and partic ularly to apparatus for making the same from rods of tungsten and other refractory metal-s.

Electrical contacts of hard material such as tungsten, or ceramics, for example, are commonly produced by cutting a rod of such material into discs and then forging or grinding the discs to obtain the desired contact surface. The rod is normally formed by the hot swaging of a sintered ingot of tungsten.

The processes heretofore employed in producing electrical contacts have been extremely costly due to the large amount of handling required to shape a contact having a generally rounded contact surface. This configuration is desired to provide a low resistance junction between contact points and aids in smoother circuit breaking by reducing arcing.

In accordance with the apparatus embodying the invention, an electrical contact with a conical surface can be produced. Also, this apparatus can be used to cut contact discs having a rounded surface by relatively moving into cutting engagement a rotating rod and a cutting device while continuously varying the angular relationship between the rod and cutting device.

The invention will be understood from the following description taken in connection with the accompanying drawings showing illustrative embodiments of the invention in which:

FIGURE 1 is a plan view of the apparatus used for producing the contact discs;

FIGURE 2 is a side elevational View of the apparatus;

FIGURE 3 is a series of enlarged and exaggerated views showing the cutting action which takes place in forming a contact disc having a conical contacting surface;

FIGURE 4 is a section taken along lines 4-4 of FIG- URE 3;

FIGURE 5 is a series of enlarged and exaggerated views illustrating the cutting act-ion that takes place when cutting a disc having a rounded contacting surface;

FIGURE 6 illustrates a finished conical contact disc;

FIGURE 7 is a schematic circuit diagram showing the mechanisms used for cutting discs having either conical or flat contacting surfaces; and

FIGURE 8 is a schematic diagram showing the operation of the apparatus when used for cutting discs having a rounded contacting surface.

Referring first to FIGURES 1 and 2, there are illustrated the primary components of the apparatus making up applicants invention. The elements disclosed in FIG- URES l and 2 will be individually described in terms of the various components, and the control means for actuating them will be explained when describing FIGURES 7 and 8.

There is shown in FIGURE .1, mounted on a machine base 1, a rod supporting, rotating and feeding assembly including a rod spindle housing 2 through which extends a cylindrical rod 3. The rod 3 is supported at one'end in a collet 4 which regulates the axial movement of rod' 3 therethrough. The rod 3 and oollet 4 are rotated by nod spindle drive motor 6, which is mounted on the spindle housing 2, through pulley 7, belt 8 and pulley 9. An air motor or equivalent device 11 (see FIGURE 2) is employed to move rod 3 axially into contact with a rod stop 12 when collet 4 is open. The rod supporting, rotating and feeding assembly is slidably mounted relative to base 1 by means of a tongue portion 13 which extends from housing 2, and a cooperating groove 14 formed in a plate 16 that is secured to base 1. The housing 2 is fixed in place relative to plate 16 by lock 17.

The rod stop 12 extends through an insulated bushing 18 which is fitted into a bracket 19. The bracket 19 is adjustably mounted relative to base 1 by a lock screw 21 that extends through slot 22 in bracket 19. Connected to the rod stop 12 by nuts 23, 24 is an electrical control wire 26 which forms part of a control circuit, described hereinafter, that effects the movement of a power driven cutoif wheel 27 and operation of collet 4.

The cut-off wheel 27 is mounted on a table 28 which is pivotally mounted relative to base 1 through pivot member 29 supported by bearings 31. In the embodiment shown, the axis 30 of pivot member 29 intersects the axis 5 of rod 3 at right angles. The table 28 is rotated about pivot 29 by hydraulic motor 32, which is secured to base 1, through piston rod 33, connecting pin 34, and connector 36. As will be described later in greater detail, the motor 32 may be continuously operated to swing table 28 about pivot 29 or may be utilized to adjust table 28 to .a fixed angle relative to base 1 as indicated at protractor 37. It can be appreciated that movement of table 28 and cut-off wheel 27 about axis 38 of pivot member 29 will cut in rod '3 a segment of a spherical surface having its center on axis 30, which surface will be hereinafter referred to as rounded. (See FIGURES 1, 5 and 8.)

Secured to base 1 is an adjustable upper stop and electrical control switch unit 39 which limits counter-clockwise rotation of table 28 and regulates the opening and closing of collet 4. When switch 39 is engaged, collet 4 is opened to allow air motor 11 to move rod 3 into engagement with rod stop 12 (see FIGURE 8). When table 23 moves away from switch 39, collet 4 is closed to clamp rod 3 against longitudinal movement. This reduces the wear on wheel 27 which would otherwise be caused by red 3 being continuously urged against wheel 27 by motor 11 during withdrawal of wheel 27. A lower limit stop and electrical contact unit 41 is also provided to effect an adjustment of the position of cut-off wheel 27 (see FIG- URE 8) to compensate for wheel wear. The operation of these devices will be described in greater detail hereinafter.

The cut-off wheel 27 used for cutting the rod into discs is a thin cutting or grinding disc that is driven at high speed by a motorized spindle 42, which extends through and is rotatably supported by spindle housing 44, and terminates in mounting spindle 48. The cut-off wheel 27 is fixed between clamping discs 46, 47 which are secured to spindle 48 by nut 49. Surrounding cut-off wheel 27 is a guard housing 51 and a guide 52 for guiding wheel 27 during the cutting operation. The cut-off wheel 27 is moved in its own plane into and out of engagement with rod 3 by hydraulic motor 53 through piston rod 54 which is con nected to spindle housing 44. The axes of wheel 27 and rod 3 are in the same plane so that a disc will be cut from rod 3 when wheel 27 reaches the position shown in FIG- URE 4. The back surface of the disc which is formed as a result of this relationship will be discussed hereinafter. The operation of motor 53 will be described in detail when discussing FIGURE 7.

The spindle housing 44 is slidably mounted relative to support 28 through a tongue 55 extending from housing 44, and a cooperating groove 56 cut into plate 57 (see FIGURE 2). The spindle housing 44 is longitudinally movable relative to table 28 through the longitudinally extending tongue portion 58 depending from plate 57 and a mating groove 59 cut into plate 61. The longitudinal position of spindle housing 44 is set by knob 62 connected to threaded rod 63 which extends through a bracket 64 and is threadedly engaged with plate 57. The plate 61 and bracket 64 are secured to table 28 so that rotation of knob s2 adjusts the position of plate 57 relative to plate 61. This longitudinal adjustment is provided to regulate the axial dimension of the discs being cut from the rod.

The range of the transverse movement of spindle housing 44 relative to table 28 is regulated by the hydraulic motor assembly 66 mounted on table 28. This motor assembly includes a piston rod 67 which extends through a bracket 68 that is part of spindle housing 44. Threadedly engaged with rod 67 on opposite sides of bracket 68 are stop nuts 69, '71 which set the limits of the transverse travel of spindle housing 44 relative to table 28. The distance between stop nuts 69 and 71 is adjusted to be equal to the width of bracket 63 and switch 74, the operation of which is described hereinafter, plus one-half the diameter of the rod being cut. Compensation for wearing of wheel 27 is taken care of by providing piston 72 of motor 66 with a check valve 73 to permit free movement of cut-off wheel 27 toward rod 3 during the cutting operation. A switch 74 is provided to open collet 4 to permit air motor 11 to move rod 3 longitudinally against stop 12 when switch 74 is closed. The switch 74 is closed when spindle housing 44 moves to its preset limit of transverse travel away from red 3 as determined by stop nut 69. When switch 74 is opened, collet 4 again clamps rod 3 in place. This operation is similar to that discussed with respect to switch 39 in that switch 74 prevents rod 3 from being continuously pressed against wheel 27 during the cutting and withdrawal movements of wheel 27. It should be noted that when tungsten is being cut, a coolant is supplied through tube 65.

It can be seen from the apparatus thus described that rod 3 can be cut into discs having a flat, conical, or rounded contacting surface as determined by the positioning of cut-off wheel 27 relative to rod 3 during the cutting operation. Flat discs will be obtained when table 28 is set at a zero angle relative to base 1 and cut-off wheel 27 is introduced normal to the axis of rod 3; conical discs will be produced when table 28 is angularly disposed relative to base 1 and cu -off wheel is moved by motor 53, as shown in FIGURES 1, 2, and 7; and a disc having a rounded contacting surface is formed when the spindle housing is maintained stationary relative to table 28 and cut-off wheel 27 is brought into cutting contact with rod 3 by actuating motor 32 to swing table 28 about pivot 29 (see FIGURES 1, 5, and 8).

Referring now to FIGURE 3, there is illustrated in enlarged and exaggerated views, for purposes of explanation, the position of cut-off wheel 27 during the various stages of cutting contacts having a conical face from rod 3. In the instant situation, the table is adjusted to a 10 angle, but this can be varied depending on the conical contact surface desired. It can be seen that the back surface of the contact being cut off is slightly concave due to the angle at which the blade is introduced and the relationship between the diameter of the cut-off wheel 27 and the diameter of rod 3 (see FIGURE 4). This concavity can be used to provide a pocket for the material used to secure the contact to its support.

Referring to FIGURE 5, there is shown the cutting action of wheel 27 when producing discs having a rounded surface. In this situation, the back surface of the contact discs being formed are flat since cut-off wheel 27 is normal to the axis 5 of rod 3 at the moment the disc is severed from the rod 3.

The operation of the apparatus to obtain contacts having the desired configuration will be seen by referring to FIG- URES 7 and 8 which schematically illustrate the operation of the various components and control mechanisms used.

Referring first to FIGURE 7, there is illustrated the control diagram for cutting cone faced discs. However, while the apparatus is set up to produce cone faced discs, it is obvious that flat discs can be obtained merely by adjusting table 28 so that cut-off wheel 27 is introduced normal to the axis of rod 3.

To cut cone faced discs, the desired setting of table 28 and cut-off wheel 27 is arrived at by positioning hydraulic A motor 32 until the desired angle is reached which will be indicated on protractor 37 (see FIGURE 1).

After table 28 is adjusted to an angle of 10, for example, motor 32 is locked in place and the cutting is performed by wheel 27 which is moved into and out of engagement with rod 3 by hydraulic motor 53 in the plane of the wheel. The motor 53 moves spindle housing 44 in groove 56 (see FIGURE 2) between stop nuts 69, 71.

The operation of motor 53 is controlled by four-way valve 76 which is positioned by solenoids 77, 78. Actuation of solenoid 77 moves valve 76 to supply fluid through flow control valve 79 to operate motor 53 to move wheel 27 into cutting contact with rod 3. When solenoid 77 is deactivated and solenoid 78 is energized, fluid is directed to motor 53 to move wheel 27 away from rod 3. The solenoids 77, 78 are controlled by relay 81 which includes coil 82 and double-throw switch 83. The coil 82 is in a circuit including power supply 84, rod 3 and stop 12. And thus, when rod 3 engages stop 12, coil 82 attracts switch 83 to energize solenoid 77 to effect movement of cut-off wheel 27 into contact with rod 3. When a disc is cut off from rod 3, the circuit including coil 82 is broken and switch 83 moves to direct current to solenoid '78 to effect movement of wheel 27 away from rod 3. When bracket 68 closes switch '74, collet 4 is opened to allow motor 11 to move rod 3 into engagement with stop 12. The infeed movement of housing 44 and consequent opening of switch 74 closes collet 4 to clamp rod 3 against longitudinal movement during the cutting and withdrawal movements of cutting wheel 27. The range of movement of spindle housing 44 is substantially equal to the distance between nuts 69, 71

minus the width of bracket 68 and switch 74. This cycle is repeated to cut oil another disc when rod 3 is axially moved into contact with stop 12 by air motor 11.

When wheel 27 begins to wear, housing 44 engages nut 71 to move piston 72 and rod 67 of motor 66 toward rod 3 to compensate for the reduction in diameter of wheel 27. This new position of rod 67 enables the wheel to cut a disc from the rod within the range of movement set by nuts 69, 71. Such movement of piston 72 is permitted by check valve 73. When wheel 27 is to be replaced, motor 66 may be actuated to return the housing 44 to its original position by push button 86 which opens solenoid valve 87 to allow fluid to flow to the underside of piston 72.

Referring now to FIGURE 8, there is shown a schematic control system for cutting discs having a rounded contacting surface. This is accomplished by moving table 28 and cut-off wheel 27 on a radius about the axis 30 of pivot 29 which axis is normal to the axis of rod 3. This is done by alternately supplying fluid to opposite sides of motor 32 to swing table 28 about pivot 29, which rotation is limited by fixed stops with electrical control switches 39, 41.

The motor 32 is controlled in accordance with the position of rod 3 in a manner similar to that described for motor 53 in FIGURE 7. Thus, when rod 3 engages stop 12, coil 88 is energized to move switch 89 to actuate solenoid valve 91 and position four-way valve 92 to direct fluid to the upper chamber of motor 32 through flow control valve 93. The actuation of motor 32 in this manner functions to rotate table 28 clockwise and bring cut-off wheel 27 into cutting engagement with rod 3. Severing the electrical contact disc from rod 3 cuts off the current in coil 88 which releases switch 89 to close the return circuit and energize solenoid valve 94. When valve 94 is opened, fluid is supplied to the lower chamber of motor 32 to rotate table 28 counterclockwise and move cut-off wheel 27 away from red 3. This cycle is repeated when rod 3 again contacts stop 12. When table 28 engages stop and electrical switch 39, collet 4 is unlocked to permit air motor 11 to move rod 3 into engagement with stop 12. The disengagement of switch 39 'closes collet 4 to clamp rod 3 against longitudinal movement during the cutting and withdrawal movements of cutting wheel 27.

When table 28 engages stop and electrical switch 41 due to wheel wear, motor 53 is operated to reposition spindle housing 44 and cut-otf wheel 27 relative to table 28 so that wheel 27 will cut 0d the disc during the normal operating range of movement of table 28. In practice, when table 28 abuts stop and electrical switch 41, solenoid 77 is energized to direct fluid to motor 53 to move spindle housing 44 and cut-off wheel 27 relative to table 28 until the disc is severed from rod 3. When the disc is cut off, coil 88 and solenoid 77 are de-energized to halt further movement of spindle housing 44. When wheel 27 is Worn down and replacement is in order, the spindle housing 44 and cutting wheel 27 may be returned to their original positions by closing switch 96 to energize solenoid 78 to direct fluid to the underside of motor 53.

Thus, it can be seen that an apparatus is disclosed which can be utilized to cut electrical contact discs having flat, conical, or rounded contacting surfaces, from a rod of electrical contact material such as tungsten. The discs produced, particularly those having a rounded or conical contacting surface, are readily usable with but a minimum of further handling required. Finished discs can thus be mass produced at a relatively low cost compared with those presently being manufactured by the more conventional forging and grinding methods.

It remains to note that the illustrated apparatus could be employed to cut discs having conical surfaces on both ends of the disc. This can be obtained by adjusting the position of the cutting wheel 27 relative to the rod 3 in a manner discussed hereinafter.

As previously mentioned, the illustrated apparatus when used for cutting discs having a conical face will form a slightly concave back surface on the disc being severed from the rod. This results from the fact that the axes of the wheel 27 and rod 3 are in the same plane. However, if it is desired to cut a disc having a conical surface on both ends of the disc the spindle housing 44 would be adjusted in a plane perpendicular to the aforementioned plane an amount equal to one-half the diameter of the cutting wheel and moved in a plane normal to this perpendicular plane until the periphery of the wheel makes contact with rod 3. Allowance should, of course, be made for necessary clearances. Due to the relative location of the rod 3 and wheel 27, the contact disc will not be severed from the rod until the conical surface is formed on both ends.

To compensate for wheel wear when cutting discs having concial surfaces on both ends, an additional hydraulic motor or equivalent device will be added to move the wheel and spindle housing in said perpendicular plane. Suitable switching mechanisms will also be provided to actuate this additional hydraulic motor in conjunction with the movement of motor 66 and associated nuts 69, 71. The position of nuts 69, 71 will be set for the range of movement of spindle housing 44 required to properly feed the cut-off wheel to sever a disc having conical surfaces on both ends from rod 3. Briefly, when wheel 27 reaches the end of its travel as determined by newly positioned nut 71 and a disc has not been cut off the additional hydraulic motor will be repositioned to move the spindle housing in said perpendicular plane to compensate for the reduced wheel diameter.

A disc having a back surface which is slightly concave near the center and conical at its periphery will be formed if the axis of wheel 27 is displaced an amount less than one-half the diameter of the wheel.

While several embodiments of the invention have been described specifically, it will be apparent to those skilled in the art that many alterations and substitutions of mechanical equivalents may be made. For example, the mechanisms disclosed for rotating and axially feeding the rod and for limiting the axial advance of the rod are but representative of the numerous devices which could be employed. Also, the elecrtical-hydraulic control systems used are merely intended to be illustrative of various types of electrical, hydraulic or pneumatic control devices which could be used to move the cutting mechanism in response to the axial movement of rod 3. Furthermore, it is obviously within the scope of this invention to use a non-rotating cutting device in place of the power-driven wheel disclosed in the drawings. And the rod used could be polygonal instead of cylindrical.

Other equivalents will occur to those skilled in the art, and it is, of course, intended to cover by the appended claims all such modifications as fall within the true spirit and scope of the invention.

1 claim:

1. In an apparatus for cutting a rod into discs including means for rotating and longitudinally moving said rod, means for limiting longitudinal movement of the rod, a base member, a table pivotally mounted on said base member, means for moving said table relative to the base member, a cutting device movably mounted on the table, means for moving said cutting device into cutting engagement with said rod, and control means responsive to the relationship between said rod and said rod limiting means for controlling the movement of the table and cutting device mounted thereon.

2. In an apparatus for manufacturing contact discs out of a rod of contact material including means for continuously rotating said rod, a rod abutment means, means for longitudinally feeding said rod against said rod abutment, a cutting device for cutting said rod into discs, means for moving said cutting device into cutting engagement with said rod and for supporting said cutting device relative to said rod, control means responsive to the relationship between said rod and rod abutment for controlling the movement of said moving and supporting means, means limiting the movement of said moving and supporting means, and means responsive to the engagement between said moving and supporting means and said limiting means to control the longitudinal movement of said rod and adjust the position of said cutting device.

3. In an apparatus for producing discs having a conical surface from an elongated rod of contact material cornprising means for rotating and axially moving said rod, means for determining the axial advance of said rod, means for cutting said rod into discs, and means for relatively feeding the cutting means into cutting engagement with said rod at an angle of less than 90 between the axis of the rod and the direction of feed of the cutting means for cutting the rod into discs having a conical surface.

4. In an apparatus for producing discs having a conical surface from an elongated rod including means for rotating and longitudinally moving said rod, means for limiting the axial movement of said rod, a base member, a cutting device slidably supported relative to said base member and including a cut-0d wheel, and control means responsive to the relationship between the rod and rod limiting means for feeding said cuting device relative to the base member and relative to said rod at an acute angle between the axis of the rod and the direction of feed of the cutting device to cut discs from the rod having a conical surface.

5. An apparatus for cutting an elongated rod into discs including a base member, a rod stop, means for rotating and axially feeding said rod into engagement with said rod stop, a table pivotally mounted on said base member, power drivencutting means including a cut-off wheel slidably mounted on said table, means for adjusting the table to locate the cut-offwheel at an acute angle relative to the axis of said rod, means for transversely moving the cut-off wheel into and out of engagement with said rod whereby the wheel cuts the rod into discs having a conical surface, control means responsive to the relationship between said rod and rod stop for controlling themovernent of said cutting means, means limiting the transverse movement of said cutting means, and means responsive to said limiting means to control the axial movement of said rod and adjust the position of said cutting means to compensate for Wheel wear.

6. An apparatus for producing electrical contact discs out of an elongated rod of contact material including means for rotating and longitudinally moving said rod, means for limiting the longitudinal movement of said rod, a cutting device, and means for continuously varying the angular relationship between the axis of the rod and the cutting device and for relatively moving the rod and cutting device into cutting relationship to cut the rod into discs.

7. In an apparatus for cutting electrical contact discs out of a rod of electrical contact material, the combination including means for rotating the rod, means for axially feeding said rod, means for limiting the axial movement of said rod, a base member, a table pivotally mounted on said base member about an axis normal to the axis of said rod, means for pivoting said table, a cutting device mounted on said table, and control means responsive to the relationship between said rod and said rod limiting means for positioning the table to bring the cutting device into contact with the rod at a continuously varying angle between the axis of rotation of the cutting device and the axis of said rod to produce a disc having a rounded contacting surface.

it. In an apparatus for cutting a rod into discs having a rounded surface, the combination including means for rotating the rod, means for axially feeding said rod, a stop for limiting axial movement of said rod, a base Cit member, a table pivotally mounted relative to said base member about an axis normal to the axis of said rod, power driven cutting means slidably mounted on said table, means responsive to the relationship between said rod and stop for swinging the table relative to said base member to move said cutting means into and out of contact with said red at a continuously varying angle between the axis of said cutting means and the axis of said rod to produce a disc having a rounded surface, means for limitin the pivotal movement of said table, and means responsive to said table limiting means to control the axial feeding of said rod and adjust the position of said cutting means.

References Cited by the Examiner UNITED STATES PATENTS 1,049,255 12/ 12 Merritt 82--47 2,019,072 10/35 Clemens 82-12 X 2,020,837 11/35 Herrmann 8211 2,262,178 11/41 Gest 82-5.5 X 2,383,741 8/45 Robinson 51-105 2,422,531 6/47 Dannehower et al. 51l05 2,445,167 7/48 Dahl et al. 51-98 2,836,015 5/58 Stone 5198 FOREIGN PATENTS 222,294 5/ 10 Germany.

WILLIAM W'. DYER, 111., Primary Examiner.

RICHARD H. EANES, 111., Examiner. 

1. IN AN APPARATUS FOR CUTTING A ROD INTO DISCS INCLUDING MEANS FOR ROTATING AND LONGITUDINALLY MOVING SAID ROD, MEANS FOR LIMITING LONGITUDINAL MOVEMENT OF THE ROD, A BASE MEMBER, A TABLE PIVOTALLY MOUNTED ON SAID BASE MEMBER, MEANS FOR MOVING SAID TABLE RELATIVE TO THE BASE MEMBER, A CUTTING DEVICE MOVABLY MOUNTED ON THE TABLE, MEANS FOR MOVING SAID CUTTING DEVICE INTO CUTTING ENGAGEMENT WITH SAID ROD, AND CONTROL MEANS RESPONSIVE TO THE RELATIONSHIP BETWEEN SAID ROD AND SAID ROD LIMITING MEANS 